Combined door knob and key fastener.



' EMIL RUEFF, OF NEW YORK, N. Y.

MAGNESIUM CEMENT AND PROCESS OF MAKING THE S AIIE.

Specification of Letters Patent.

Patented Dec. 8, 1907.

Application filed April 19. 1907- Serial No. 369.041.

To all whom it may concern:

Be it known that I, EMIL RUEFF, a citizen ;of the United States, and aresident of the p eric influences, and which, when mixed with water,will form a dense stonelike mass clagable of use in positions exposed tothe i uence of moisture. I

My cement is obtained by mixing powdered magnesia with powderedmagnesium sulfate in amorphous condition. I am aware of the fact thatcement has already been made by mixing magnesia and commercial magnesiumsulfate, the latter being the crystalline substance known in the tradeas Epsom salt. (See U. S. patent to Jeroch,- No. 833,930, October 23,1906, for magnesium cement.) This crystalline magnesium sulfate cannotbe ground to a fine amorphous powder. It is'too readily soluble inWater, and, when mixed with magnesia and water, recrystallizes quicklyand does not combine in sufficient quantity chemically with themagnesia, but causes the resultant stone to be brittle and easilydisintegrated when placed under water.

I destroy the crystalline character of the magnesium sulfate in themanner hereinafter described and produce an amorphous mass which canreadily be powdered to any desired degree of fineness. When theamorphous powder obtained b grinding this mass is mixed with calcinemagnesite, and

-water is added to the resultant mixture, a

chemical. reaction takes place as indicated by the heat developed, and aproduct results which may be called a basic sulfate of magnesia. Thisproduct is a dense mass which has strong cementing qualities.

My cement is manufactured in the following manner: I heat, slowly, Epsomsalt (MgSOJH OL keeping it at a tem erature of about 140 C. until waterof crysta ization has been driven off to the amount of from' 35 to 40per cent. of the original weight of the Epsom salt. The resultingsubstance, dehydrated magnesium sulfate, (substantially M S0 E 0) is anamorphous flaky mass. his is ground to a fine powder and mixed withpowdered magnesia. This magnesia may be obtained from magnesite bycalcination' or from dolomite heated to a point at which only thecarbonic acid in combination with ma esia is driven out.

I have found that T may use in lace of the epsom salt finely powderedkieserite, which mineral contains a large percentage of substantiallypure magnesium sulfate in amor hous condition, (substantially MgSO,H 8).I may, of course, dehydrate the Epsom salt in the usual manner by quickheating, but in that case the substance first fuses in its own water ofcrystallization, and, when such water is driven off, a hard mass remainswhich must be subjected to a great deal of grinding before it assumesthe divided form which results from my improved method of slowdehydration described above. I prefer "to mix the two ingredients insubstantially the proportions of 135 parts by Weight of powderedmagnesium sulfate in amorphous condition to 200 of magnesia.

The dry cement, in powder form, is packed in barrels and is then readyfor shi ment. It is non-hygroscopic and may there ore be shipped longdistances, and over seas, and may be kept for a long time. At the placeof use it is mixed with the desired quantity of filling materials andwith an amount of water sufficient to bring it to a pasty consistency.It then hardens slowly, because of the slow solubility of the magnesiumsulfate in amorphous condition. As already explained, the magnesiumsulfate, instead of recrystallizing rapidly, and thus weakening thestone, combines chemically with the magensia. The slow hardenin resultsin the formation of a denser and arder mass than that obtained by theuse of crystallized magnesium sulfate.

The hardened cement has a hard smooth surface and is remarkably toughand durable; it possesses great crushing and tensile strength andadheres rigidly to wood and iron. It may therefore be used to greatadvantage, when mixed with powdered-or crushed minerals, formanufacturing artificial stone, slates and tiles. If mixed with porousmaterials, such as cork. wood, wood pulp, asbestos and other fibroussubstances, it can be used for manufacturing isolating parts by weightPATENTED DEO.'3, 1907.

0. H. RUEL. COMBINED DOOR KNOB AND KEY PASTENER.

APYLIOATION FILED NOV'.14. 1906. RENEWED JULY 27, 1907' awuentozwilnaaoea c. cRRls PETEhS co w 70. n

